Exercise builds muscle strength, which protects joints. And movement is needed to get synovial fluid, a substance that nourishes and lubricates joints, to circulate over the joint. But many people with arthritis are not physically active. They may avoid exercise because they believe it will be painful, they are afraid of damaging their joints or they fear falling. And not enough people with osteoarthritis see a physical therapist, who can develop a personalized exercise program according to your preferences and needs.